This did not change the inherently adversarial nature. It just obscured it by adding a veneer of "see? our interests are the same as your interests!", despite this being true of just one (small) aspect of the union of all interests.
No, the dilemma with employers and employees comes from the differing numbers thereof.
The fact that there are (relatively) few employers, and that these employers have already chosen to seek their fortune (or that of their shareholders) by tapping the excess value of their employees, means that it is much easier for their interests to all align, without coordination.
However, the vastly greater numbers that make up the employees have no natural alignment, and tend to be too diverse in their own personal agendas to align even deliberately.
This asymmetry is the principle reason why unions, though imperfect, are a great idea. They attempt to gloss over the vast range in the agendas of individual employees by forcing employers to deal with an aggregate. The alignment of interests among the employees may not be perfect with a union, but it is a lot closer than it would be otherwise, and can offer (sometimes) a real balance to the easily aligned interests of employers.
The inherent problem with a union is that, unlike with metalworkers, stonemasons or train drivers, there is still no way to tell a capable software developer from a bootcamp wannabe, and people in the same position can differ 10-100x in output.
Call me an elitist gatekeeper, I don't want to pay dues to protect dunces and have my employers keep paying them.
